Simplify the Expression Algebraically $\cos ( 6 x + 9 y ) + \cos ( 6 x - 9 y )$

question 23

Multiple Choice

Simplify the expression algebraically.​ $\cos ( 6 x + 9 y ) + \cos ( 6 x - 9 y )$ ​

• A) \(\cos 6 x\)
• B) \(\cos 6 x \cos 9 y\)
• C) \(2 \cos 6 x \cos 9 y\)
• D) \(2 \cos 6 x\)
• E) \(2 \cos x \cos y\)

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Definitions:

Animatism

The belief that nature is enlivened or energized by an impersonal spiritual force or supernatural energy, which may make itself manifest in any special place, thing, or living creature.

Priests

Priests are religious leaders authorized to perform sacred rituals and guide individuals in matters of faith within various religions.

Priestesses

Female religious leaders or practitioners who perform sacred rites and ceremonies in various religious traditions.

Kinship Network

The web of social relationships that form an important part of the social structure in many cultures, based on ancestry, marriage, or adoption.